The subject system utilizes a combination of well documented principles of operation in a novel manner, the system being highly effective in the modification and control of the fuel/air combustion process of internal combustion engines. The subject improvement does not alter the design of the basic engine although it does reduce the need for external exhaust treatment devices for control of emissions. The system does provide for a cooler running engine, increased gas mileage (improved fuel economy), increased engine torque, reduction of objectionable emissions, increased engine performance, substantial elimination of ping and knock, and, finally, reduced carbon buildup.
With respect to the combustion process in internal combustion engines, certain remarks will be made herebelow about the way a hydrocarbon fuel burns in an internal combustion engine, as well as the effect the fuel/air ratio has on the three main atmospheric contaminants discharged by such engine. These are limited by federal law and include CO (Carbon Monoxide), HC (unburnt hydrocarbons) and NOX (oxides of nitrogen).
For various reasons, a "chemically correct" mixture of fuel and air does not always get the best results by way of limiting contaminating exhaust emissions. Thus, ideally, for maximum power, the fuel/air mixture should be relatively richer, having a greater proportion of fuel. On the other hand, the fuel/air mixture should be leaner, utilizing less fuel than "chemically correct", for the best economy.
Unfortunately, most of the steps that can be taken to reduce the amounts of CO and HC also tend to increase the NOX emission, with some loss in economy. For example, running at moderately lean mixtures, that is, with some excess air, promotes complete combustion. This minimizes the amount of CO and HC developed, but it also increases the combustion temperature to the point that the nitrogen in the air becomes involved in the reaction, causing highly poisonous oxides of nitrogen to be generated.
Other factors and conditions can effect the internal combustion process, such as flame propagation throughout the explosive mixture, method of ignition, duration of ignition and turbulence, to name a few.
Of the named factors, turbulence is the most important. Upon turbulence depends the rate at which combustion takes place and efficiency of the combustion process. Turbulence is set up by the gases during their entry into the combustion chamber and, for rapid flame propagation, the fuel/air mixtures must be in a high rate of turbulence. If the combustion mixture were completely quiescent at the time of ignition, flame propagation would be so slow that, even in a slow speed engine, scarcely half of the fuel/air mixture would be burned before the exhaust valve open. Further, turbulence becomes more important as the density of the charge is latered by residual exhaust products. As the latter tend to be increased, they decrease the flame temperature and thereby retard the rate of flame propagation.
Further, during periods of severe engine operating conditions, such as high loading at slow speed or engine overheating, the combustion process can be further disrupted with very undesirable results. These combustion process undesirables are known as: pre-ignition, auto-ignition and detonation. These processes produce similar results, although they are caused by different actions. Of the three noted undesirable processes, detonation is the most undesirable and should be eliminated. It is the one responsible for drop in engine performance. Further, if detonation is to act in the engine for long periods, it may lead to engine damage.
Detonation is most noticeable at full throttle/slow speed operation. It occurs when the rise in temperature and pressure of the unburnt combustion gases are sufficient to produce auto-ignition. The increase in temperature in the unburnt mixture, often referred to as end-gas, is due to an additional amount of heat received by combustion and radiation from the approaching flame front. The increase in pressure is due to pressure waves transmitted at sonic speed from the burning section of the mixture. Further, when auto-ignition occurs, the burning is practically instantaneous and has the nature of an explosion. Simultaneously, very rapid pressure increases take place. These are responsible for shock waves which impinge upon the cylinder head and cylinder walls, producing the characteristic high pitch knocking sound.
At the present time, there are several methods used for the prevention of detonation. These include retarding the spark, using fuel with higher octane numbers or by the injection of the internal coolant such as water or water/alcohol solution.
Since early 1971, the automobile manufacturers of the United States have been required by law to reduce exhaust emissions, improve fuel economy and to increase performance in internal combustion engines. However, in order to accomplish these desired results, modification of the basic combustion process (as an alternative means for producing the three desired results) has received less attention than the addition of costly retrofit exhaust treatment devices such as thermal and/or catalytic oxidation of hydrocarbon and carbon monoxide in the engine exhaust system. Nitrogen oxide generation has been reduced to some extent through a combination of retarded spark ignition timing and exhaust gas recirculation, both factors serving to diminish the severity of the combustion process.
With respect to water injection, tests were carried out by a Mr. Benki, in Hungary, before 1900 and thereafter by numerous researchers both in this country and abroad. These tests showed that the use of the internal coolant such as water had the power to prevent pre-ignition and detonation. In the early days, detonation, especially, was a severe problem because of the low octane value of the fuel available and the trend toward increasing the compression ratio of engines to obtain higher efficiency.
In 1913, a professor B. Hopkinson, in England, carried out extensive tests with water as an internal coolant for horizontal gas engines. So successful was the method that Professor Hopkinson used, that he designed engines without water jackets, using internal cooling only. Oil engines designed in the middle 1920's, for tractor work, with hot bulb ignition, were commonly fitted with water injection equipment to prevent detonation.
Developments in super charged aircraft engines in the time interval from World War I and to the beginning of World War II brought water injection back to life. During World War II, water and water/alcohol injection were used to great success, particularly at take-off and during maximum flight speed.
After World War II water and water/alcohol injection experience was gained from such use as internal coolants for truck engines and tractor engines. During the period from 1944 to 1959 water injection was particularly researched by several universities in this country, England, Canada and Australia. More than 55 papers have been written on the subject.
With respect to water vapor, as opposed to water injection, per se, it was not until after World War II, when certain German technical documents were translated into English, that two researchers, while conducting combustion gas experiments had found, for example, that the combustion velocity of carbon monoxide and air mixtures increases from 6.3 inches/second for a dry mixture to about 21.6 inches/second for mixtures containing 9.4 percent water vapor. These investigators were Ubbelohde and Dommer, reporting in Gas U. Wasserfach 1914. Other researchers in Germany verified these facts and carried tests further in which they found and reported that the combustion velocity of carbon monoxide was not only accelerated by water vapor but also by hydrogen, as well as organic compounds containing hydrogen. This was interpreted as a sign that OH radicals and perhaps H-atoms participated in the reaction. Their presence would in themselves accelerate the reaction, as well as also increase the combustion velocity indirectly by diffusing very rapidly. (K. Bunte and associates in Gas U. Wasserfach 1932)
Other research papers substantiate the influence water vapor has on turbulence, flame propagation and flame velocity.
B. W. Bradford reported in J. Chem Society 1933, P.73 that catalytic combustion of CO on quartz surfaces is inhibited by liquid water, whereas the gas reaction is greatly accelerated by water vapor.
From the above background, it became apparent to the applicant that water vapor, when properly introduced and mixed in fuel/air mixtures, for combustion, in internal combustion engines would be the ideal internal coolant. This would be not only for increased engine performance, but also for fuel economy and limiting the generation of and discharge of the three main atmospheric contaminants. Specifically, carbon monoxide, unburnt hydrocarbons and oxides of nitrogen.